Simple JavaScript problem: onClick confirm not preventing default action

There's a typo in your code (the tag a is closed too early). You can either use:

<a href="whatever" onclick="return confirm('are you sure?')"><img ...></a>

note the return (confirm): the value returned by scripts in intrinsic evens decides whether the default browser action is run or not; in case you need to run a big piece of code you can of course call another function:

<script type="text/javascript">
function confirm_delete() {
  return confirm('are you sure?');
}
</script>
...
<a href="whatever" onclick="return confirm_delete()"><img ...></a>

(note that delete is a keyword)

For completeness: modern browsers also support DOM events, allowing you to register more than one handler for the same event on each object, access the details of the event, stop the propagation and much more; see DOM Events.

Well, I used to have the same problem and the problem got solved by adding the word "return" before confirm:

onclick="return confirm('Delete entry?')"

I wish this could be heplful for you..

Good Luck!